Extensively Drug-Resistant Pseudomonas aeruginosa Bacteremia in Solid Organ Transplant Recipients

Background. We sought to determine the risk factors, molecular epidemiology, antibiotic therapy, and outcomes of bacteremia because of extensively drug-resistant (XDR) Pseudomonas aeruginosa in solid organ transplant (SOT) recipients. Methods. All episodes of bacteremia occurring in SOT recipients were prospectively documented from 2007 to 2013. Results. Of 318 episodes of bacteremia, 49 were caused by P. aeruginosa. Thirty-one strains (63%) were XDR defined by nonsusceptibility to at least one agent in all but two or fewer antipseudomonal antimicrobial categories. Time from transplantation to bacteremia was shorter in XDR P. aeruginosa group comparing to other etiologies (median days 66 vs. 278; P=0.03). Factors independently associated with XDR P. aeruginosa bacteremia were prior transplantation, nosocomial acquisition, and septic shock at onset. XDR P. aeruginosa isolates belonged to a single clone (ST-175). Comparing to other etiologies, patients with bacteremia because of XDR P. aeruginosa more often received inadequate empirical antibiotic therapy. Persistence of bacteremia, shock, respiratory failure and intensive care unit admission were more frequent in patients with XDR P. aeruginosa. The overall case-fatality rate was higher among patients with XDR P. aeruginosa bacteremia than in the others (38% vs. 16%; P=0.009). Conclusion. Bacteremia because of XDR P. aeruginosa should be carefully considered when selecting empirical antibiotic therapy for hospitalized SOT recipients with prior transplantation presenting with septic shock.